The project, with a current price tag of $30.2 million, would allow migratory fish such as sturgeon, American shad and striped bass to access spawning habitat upstream.
Currently, those species are blocked by the 76-year-old lock and dam, which has lapsed into disrepair since the corps halted maintenance of the structure – and the river’s navigation channel – in 1979.
The fish passage project has become increasingly complex – and costly – since it was proposed in 1999, when the price estimate was $7 million.
Although the adjoining lock and dam are in need of renovations, the Army Corps of Engineers’ current plan includes only the fish passage structure, which is part of the mitigation plan for the $652 million deepening of Savannah Harbor.
According to a fact sheet released this week by the corps, the new design is known as an “off-channel rock ramp” and would look like a collection of boulders that create rapids in the river.
The structure would provide a constant flow through the boulders as long as the river’s total flow is at least 8,000 cubic feet per second.
If flows fall below that benchmark, the five gates in the dam would remain closed to allow 100 percent of the river’s flow to pass through the rock ramps.
Similarly, the corps summary said, if flows exceed 8,000 cubic feet per second, the gates can be opened to allow water to dissipate downstream.
The operating plan for the project includes five years of monitoring after construction to ensure that it fulfils its purpose.
Although funds from the Savannah Harbor project are expected to finance the fish passage plan, no money has been allocated for the renovation of the lock and dam.
The corps, which built the structure in 1937, concluded in 1999 that the dam no longer served commercial shipping – the purpose for which it was built. Its plan to demolish the structure was opposed by local governments and industries that rely on its pool of water.
In August, a consortium of stakeholders, including Augusta-Richmond County and North Augusta, agreed to finance a $300,000 federal study to gather new data on the cost and scope of the dam’s needed renovations. Once repaired, ownership of the project – and its maintenance responsibilities – would be turned over to the consortium.
Corps spokesman Billy Birdwell said the new study could be launched soon.
He said that the corps recently obtained congressional approval to negotiate an agreement with the consortium, under which the corps would accept the funds needed to complete the study.
“We haven’t started those negotiations, as the approval just came earlier this month,” Birdwell said, “but we are moving forward.”
Other members of the stakeholders’ consortium include Aiken County, DSM, Kimberly-Clark, General Chemical, Potash Corp. and South Carolina Electric & Gas Co.